Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of the first image of a display screen or portion thereof with transitional graphical user interface showing a first embodiment of our new design;

FIG. 2 is a front view of a second image of the first embodiment;

FIG. 3 is a front view of a third image of the first embodiment;

FIG. 4 is a front view of a fourth image of the first embodiment; and,

FIG. 5 is a front view of a fifth image of the first embodiment.

In the images, the claim is directed to the large rectangles, and the grey tones and the highlighted circles. The remainder of the lines are broken and illustrate portions of the animated graphical user interface that forms no part of the claimed design. The dot-dashed broken line showing of the display screen or portion thereof is for the purpose of illustrating environmental structure and forms no part of the claimed design.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-5 of the first embodiment. The process or period in which one image transited to another image forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 